I'm not sure how warm much of anything will stay after 30 minutes, but this is quick and easy AND easily-transportable (just cover with foil and go!).
Easy Chicken & Rice
4 1/2 cups water
1 bouillon cube
4 boneless skinless chicken breasts
1 cup rice
2 cups broccoli florets
2 cans cream of chicken soup
Boil water and add bouillon.
Place chicken, rice, and broccoli in a 13x9 inch pan. Pour soup and water over pan. Sprinkle with seasonings.
Bake at 350 degrees for 1 hour.
Even a fish wouldn't get into trouble if he kept his mouth shut.